Apparatus for obtaining a fixing in a wall

ABSTRACT

A fixing in a wall is made by drilling a hole, inserting the pin of a nozzle mounted on a hot melt gun into the hole and injecting molten polypropylene into the space between the pin and the hole. The polypropylene is allowed to solidify and the nozzle is removed leaving a wall plug ready for the insertion of a screw. Three embodiments of a nozzle especially adapted for use in this process are described. nozzle has a hollow screw-threaded base with a pin extending forwardly therefrom. Passageways in the base each communicate at one end with the interior of the base and at another end externally of the base and the pin in the vicinity of the junction between the pin and the base. A flexible seal is slidably mounted on the base and resiliently biased towards the pin.

This is a division of application Ser. No. 918,154, filed Oct. 14, 1986now U.S. Pat. No. 4,674,257.

FIELD OF THE INVENTION

This invention relates to nozzles for use in obtaining a fixing in awall.

BACKGROUND OF THE INVENTION

Conventionally wall fixings are made by drilling a hole of theappropriate size in a wall, inserting a plug of fibrous or plasticsmaterial into the hole, and driving a screw into the plug.

In order to obtain a good fixing it is essential that the hole should beof the correct diameter to accommodate the plug. Thus, it is necessaryfor the handyman to carry a range of masonry drills and a range of plugsof different diameters to make satisfactory fixings with different gaugescrews.

Even with a comprehensive range of drills the situation occasionallyarises that the masonry surrounding the drill spalls and falls away thusleaving an irregular cavity usually of considerably greater size thanthat originally intended and totally unsuitable for the insertion of aplug. In such situations it has been proposed, for example in UK - PSNo. 470,761 to ram a moist mixture of fibers and a settable material,such as cement, into the irregular cavity. A screw may be inserted inthe mixture either before or after it has set. The material may be boredaxially with a sharp instrument before the screw is inserted.

This procedure has several disadvantages. Firstly, great care must betaken to ensure that the mixture of fibers and settable material isrammed into the interior of the cavity and does not simply form ashallow plug immediately adjacent the entrance to the cavity. Secondly,when spalling does occur it frequently extends to one or other side ofthe original hole. Once the cavity has been filled and the mixture setit is often difficult to relocate the site of the initial hole with theresult that an attempt may be made to locate a screw through a surfacelayer of the mixture and brickwork rather than into a hole filled withmixture.

SUMMARY OF THE INVENTION

The present invention, at least in its preferred embodiments, aims toreduce the above disadvantages.

According to the invention in the parent application Ser. No. 918,154there is provided a method of obtaining a fixing in a wall which methodcomprises the steps of making a hole in the wall, placing a pin in saidhole, inserting a viscous setable material into the space between saidpin and said hole, withdrawing said pin from said hole, and driving ascrew into said material.

The hole is ideally made with a drill which is greater in diameter thanthe diameter of the screw. However, because the viscous material willconform to the shape of the hole the hole can be formed in other ways,for example using a cold chisel and a hammer.

The screw may be driven into the viscous setable material either when itis partially set or when it is fully set.

Preferably, the screw is driven into the bore left on removal of thepin, this is not however essential.

The material is preferably a thermoplastics material, for examplepolypropylene which may conveniently be heated until it is extrudableand extruded into the space. A hot melt gun can conveniently be used forthis purpose.

The present invention provides a nozzle for use in a method as above.The nozzle comprises a base, a pin which extends from said base and canbe inserted into a hole in a wall, a passageway for conducting, in use,viscous setable material to the space between said pin and said hole,and a resilient member circumjacent said pin which, when said pin isinserted in said hole, forms a seal which inhibits the egress of viscoussetable material from said hole.

In one embodiment, the passageway extends along said pin and opens at oradjacent the tip thereof.

In another embodiment, the passageway opens adjacent the root of saidpin. This embodiment may also include a further passageway which extendsalong said pin and opens at or adjacent the tip thereof.

The resilient member may be arranged to form, in use, a seal with thesurface of said wall circumjacent said hole.

Preferably, the resilient member is provided with one or more groovesthrough which, in use, material can escape when said space between saidpin and said hole is full.

Preferably, the resilient member is mounted on a collar which isslidably mounted on the base of said nozzle.

Advantageously, means are provided which bias the collar towards the tipof the pin.

If desired, the arrangement may be such that the collar can moverelative to the base to an extent that when the resilient member isurged against a wall circumjacent a hole part of the base enters thehole. This is particularly useful where it is desired that the finishedwall plug should not extend flush with the surface of the wall.

The passageway may open in a plane substantially parallel orsubstantially perpendicular to the longitudinal axis of the pin. In theformer case when the nozzle is not in use, the collar is preferablyarranged to overlie the passageway and inhibit the flow of materialtherefrom.

If desired, the pin may be removably mounted on the base of the nozzle.

The pin itself is preferably tapered towards its free extremity tofacilitate removal from the hole as the material sets and may be coated,if desired, with a release agent. Alternatively it may comprise amaterial such as polytetrafluoroethylene.

In another embodiment, the resilient member comprises a layer ofcompressible material circumjacent said pin.

Preferably, the base comprises a threaded portion for threadedengagement with a hot melt gun, said resilient member grips said pin,and the periphery of said resilient member is provided with ribs tofacilitate the rotation of said nozzle about the axis of said threadedportion.

Preferably, the ribs extend parallel to the longitudinal axis of thepin.

Advantageously, the base includes a pressure plate which extends in aplane perpendicular to the longitudinal axis of said pin and which abutsone end of said resilient member.

Preferably, the resilient member is generally conical.

Advantageously, said pin is provided with a conical portion whichexpands towards the root of said pin and protects the forward portion ofsaid resilient member.

It will be appreciated that in order to accommodate screws of differentgauges and lengths a set of different pins is desirable. For thispurpose each nozzle could be provided with a set of different pins.However, it is more practical to provide a set of nozzles having pins ofdiffering lengths and/or mean diameter.

The present invention also provides a hot melt gun provided with anozzle in accordance with the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention reference will now be made,by way of example, to the accompanying drawings in which:

FIGS. 1 to 3 show steps in accordance with use of the invention forobtaining a fixing;

FIG. 4 is a side elevation of one embodiment of a nozzle in accordancewith the invention mounted on a hot melt gun;

FIG. 5 is a view, mainly in cross section, showing the nozzle ready foruse;

FIG. 6 is a view, mainly in cross section, showing a second embodimentof a nozzle in accordance with the invention mounted on a hot melt gun;

FIG. 7 shows the nozzle of FIG. 6 in use; and

FIG. 8 is a view, partly in section, of a third embodiment of a nozzlein accordance with the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1 to 3 of the drawings, there is shown a wall 1 of,for example, lightweight blocks in which it is desired to obtain afixing.

Firstly, as shown in FIG. 1, a hole 2 is drilled in the wall 1.

Secondly, as shown in FIG. 2, a pin 3 of a nozzle 4 is inserted in thehole 2 and polypropylene in its melt state is injected into the spacebetween the pin 3 and the inside of the hole 2.

Finally, after the space between the pin 3 and the inside of the holehas been filled, the polypropylene is allowed to solidify. The pin 3 isthen withdrawn leaving a bore 5 for the insertion of a screw 6.

Referring now to FIGS. 4 and 5, polypropylene in its melt state isinjected into the space between the pin 3 and the inside of the hole 2using a conventional hot melt gun 7 provided with a novel nozzle 4. Inparticular, a rod 8 of polypropylene is advanced by a trigger 9 into aheater 10 where it is heated to approximately 175° C. The polypropylenemelts and further pressure on the trigger 9 extrudes the viscouspolypropylene through the nozzle 4.

The nozzle 4 comprises a base 11 and a pin 3 which are made ofaluminium. The base 11 comprises a hollow threaded portion 12 whichengages a corresponding thread in the tip of the hot melt gun 7.

Five passageways 13 are disposed around the root of the pin 3 andcommunicate with the interior of the hot melt gun 7.

The radial outer surface of the base 11 of the nozzle 4 comprises aportion 14 of reduced diameter. A collar 15 is slidingly mounted on thisportion 14 and is biased towards the tip 16 of the pin 3 by a spring 17circumjacent the portion 14 of the base 11. A pin (not shown) preventsthe collar 15 sliding off the portion 14.

A flexible seal 18 of thermoplastic rubber is mounted on the collar 15.

It will be noted that the pin 3 is tapered towards its tip 16.

As can clearly be seen from FIG. 5, the hole 2 is made slightly longerthan the length of the pin 3. As the pin 3 is inserted into the hole 2the flexible seal 18 comes into contact with the wall 1 surrounding thehole 2. As the pin 3 is inserted further the collar 15 compresses thespring 17. The spring 17 is fully compressed when the leading face 19 ofthe base 11 is flush with the wall surrounding the hole 2.

When the trigger 9 is depressed the viscous polypropylene, which istypically at 175° C., passes through the passageways 13 at a pressure ofapproximately 7×10⁵ Pa. The viscous polypropylene enters andsubstantially fills the space between the pin 3 and the hole 2. The sealbetween the wall 1 and the flexible seal 18 is sufficient to ensure thatthe viscous polypropylene penetrates substantially all the availablespace. Heat from the heater 10 is transmitted to the base 11 of thenozzle 4 via the hollow threaded portion 12 thereby ensuring that thepolypropylene does not solidify in the passageways 13. Injection ofmolten polypropylene is continued until the hole 2 is full. This can bedetected by the appearance of plastics material from around theperiphery of the flexible seal 18. For this purpose the leading face 20of the flexible seal 18 is provided with six small radially extendinggrooves, one of which (groove 21) is shown.

The polypropylene starts to solidify after about 5 seconds and thenozzle 4 is then withdrawn leaving a bore 5 corresponding to the pin 3which is ready after a further minute or so to receive a screw 6 to makea firm and secure fixing.

Various modifications to the nozzle 4 are envisaged. For example, thepin 3 could be threadedly mounted to the base 11. In such an embodimentthe pin could be made of a different material, for example,polytetrafluoroethylene (PTFE). The nozzle 4 could comprise one of a setof similar nozzles, each with the same hollow threaded portion 12 forattachment to the hot melt gun 7 but having different pins to providebores for screws of different lengths and/or gauges.

In addition, the flexible seal 18 and associated structure could bedispensed with although this is not recommended.

Materials other than polypropylene are also suitable, for exampleelastomers and synthetic rubber, for example neoprene. Such materialsshould not shrink appreciably on cooling. Polyamide 6 may beparticularly suitable.

If desired, the nozzle may be adapted so that hot polypropylene isinhibited from passing through the passageways when the nozzle is not inuse. Such an arrangement is shown in FIGS. 6 and 7. In particular, thenozzle 4' comprises a base 11' having a first portion 22, a secondportion 14' and a threaded portion 12'. A stepped collar 15' is slidablymounted on the second portion 14' and is urged towards an abutmentformed by the side 23 of the first portion 22 by a spring 17' which actsbetween the stepped collar 15' and a flange 24 force fitted on the base11'. A bore 25 extends through the threaded portion 12' and the secondportion 14' and terminates in the first portion 22 immediately adjacentthe root of the pin 3'. Five passageways 13' extend radially outwardlyfrom the bore 25 and open in the periphery of the first portion 22.

When the nozzle 4' is not in use, (FIG. 6) the spring 17' urges thestepped collar 15' towards the tip 16' of the pin 3'. One part 26 of thestepped collar 15' engages the side 23 of the first portion 22 whilstthe other part 27 covers the outlets of the passageways 13'.

When the nozzle 4' is in use, (FIG. 7) insertion of the pin 3' in thehole 2' causes the flexible seal 18' and the collar 15' to be displacedrelative to the base 11' to open the passageways 13'. Hot polypropylenecan then be injected via the passageways (which are typically 1 to 3 mmin diameter) into the space between the pin 3' and the hole 2'. Sincethe bore 25 extends to a position immediately adjacent the base of thepin 3', the pin 3' can be kept relatively hot which inhibits thepolypropylene setting before the space between the pin 3' and the hole2' is filled.

Where the wall comprises blocks covered with plaster it is desirablethat the fixing should be made in the block rather than in the plaster.In such a situation a hole is drilled through the plaster and the block.However, only the block is filled with plastics material. To inhibitplastics material being present in the plaster the nozzle is shaped sothat when the flexible seal is urged against the wall the leading faceof the base penetrates the hole until it is flush with the face of theblock. Naturally, a small amount of plastics material around theperiphery of the hole in the plaster will not be harmful provided thatthe screw does not exert appreciable radial forces on it which mightotherwise crack the plaster.

As mentioned earlier, hot, viscous plastics material can be introducedthrough the tip of the pin provided that solidification will not occur.

FIG. 8 shows a particularly inexpensive nozzle which is generallyidentified by reference numeral 4". The nozzle 4" comprises a baseportion 11" and a pin 3" which is formed integrally therewith. Apressure plate 30 is mounted on the base 11" and extends in a planeperpendicular to the longitudinal axis of the pin 3". The pin 3" has aconical portion 31 which expands towards the root of the pin 3" andprotects the leading portion of a flexible seal 18" made of a resilienthigh temperature silicon rubber.

The outer surface of the flexible seal 18" is provided with a pluralityof ribs 33 which extent parallel to the longitudinal axis of the pin 3".

The base 11" has a hollow threaded portion 12" which contains astainless steel ball 34 which is biased against a valve seat formed byone end of an insert 35 by a spring 36.

In use, the nozzle 4" is mounted on a hot melt gun via the hollowthreaded portion 12". The ribs 33 facilitate this operation, torquebeing transmitted via frictional engagement between the flexible seal18" and the pin 3".

When the pin 3" is inserted into a hole the flexible seal 18" engagesthe side wall of the hole and forms an adequate seal therewith. Moltenpolypropylene is then delivered from the hot melt gun through thepassageway 13" of nozzle 4" by repeatedly actuating the trigger on thehot melt gun. In the case of a large hole part of the ribs 33 may enterthe hole. However, it has been found that this barely impairs the sealbecause of the resilient nature of the flexible seal 18" and theinherently irregular surface of the hole.

When the space between the pin 3" and the hole is filled the trigger onthe hot melt gun is released. The nozzle 4" is then withdrawn leaving abore ready to receive a screw. The stainless steel ball 34 returnsagainst the insert 35 under the influence of spring 36 and inhibitsmolten glue dripping from the nozzle 4".

What is claimed is:
 1. A nozzle for use in a method of obtaining afixing in a wall which method comprises the steps of making a hole inthe wall, placing a pin in said hole with a space between the pin and abounding interior surface of said hole, inserting a viscous setablematerial into said space, withdrawing said pin from said hole anddriving a screw into said material, which nozzle comprises:a base; saidpin which extends from said base and can be inserted into said hole insaid wall; a passageway in said nozzle for conducting, in use, viscoussetable material to the space between said pin and said hole; aresilient member circumjacent said pin which, when said pin is insertedin said hole, forms a seal which inhibits egress of said viscous setablematerial from said hole; said resilient member being provided with oneor more grooves through which, in use, material can escape when saidspace between said pin and said hole is full; and said resilient memberbeing mounted on a collar which is slidably mounted on said base of saidnozzle.
 2. A nozzle as claimed in claim 1, wherein said passagewayextends along said pin and opens at or adjacent a tip thereof.
 3. Anozzle as claimed in claim 1, wherein said passageway opens adjacent aroot of said pin.
 4. A nozzle as claimed in claim 1, including means forbiasing said collar towards a tip of said pin; and wherein said collarcan move relative to said base to an extent that when said resilientmember is urged against a surface of said wall circumjacent said hole,part of said base enters said hole.
 5. A nozzle for use in a method ofobtaining a fixing in a wall which method comprises the steps of makinga hole in the wall, placing a pin in said hole with a space between thepin and a bounding interior surface of said hole, inserting a viscoussetable material into said space, withdrawing said pin from said holeand driving a screw into said material, which nozzle comprises:a base;said pin which extends from said base and can be inserted into said holein said wall; a passageway in said nozzle for conducting, in use,viscous setable material to the space between said pin and said hole; aresilient member circumjacent said pin which, when said pin is insertedin said hole, forms a seal which inhibits egress of said viscous setablematerial from said hole; said passageway opening in a planesubstantially parallel to the longitudinal axis of said pin and alsoopening in a position such that when said nozzle is not in use saidcollar overlies said passageway and inhibits the flow of materialtherefrom.
 6. A nozzle according to claim 5, wherein said pin is taperedto facilitate removal from said material.
 7. A nozzle for use in amethod of obtaining a fixing in a wall which method comprises the stepsof making a hole in the wall, placing a pin in said hole with a spacebetween the pin and a bounding interior surface of said hole, insertinga viscous setable material into said space, withdrawing said pin fromsaid hole and driving a screw into said material, which nozzlecomprises:a base; said pin which extends from said base and can beinserted into said hole in said wall; a passageway in said nozzle forconducting, in use, viscous setable material to the space between saidpin and said hole; a resilient member circumjacent said pin which, whensaid pin is inserted in said hole, forms a seal which inhibits egress ofsaid viscous setable material from said hole; said resilient membercomprising a layer of compressible material circumjacent said pin; saidbase comprising a threaded portion for threaded engagement with a hotmelt gun; said resilient member gripping said pin; and a periphery ofsaid resilient member being provided with ribs to facilitate rotation ofsaid nozzle about an axis of said threaded portion.
 8. A nozzle asclaimed in claim 7, wherein said ribs extend parallel to a longitudinalaxis of said pin.
 9. A nozzle as claimed in claim 8, wherein said baseincludes a pressure plate which extends in a plane perpendicular to saidlongitudinal axis of said pin and abuts said resilient member.
 10. Anozzle as claimed in claim 9, wherein said resilient member is generallyconical, and said pin is provided with a conical portion which expandstowards a root of said pin and protects a forward portion of saidresilient member.
 11. A nozzle for forming a plug in a hole in a wall,said nozzle comprising:a screw-threaded hollow base for detachablyscrewing the nozzle to a hot melt gun; a tapered pin connected to andextending away from said base in a forward direction along a centrallongitudinal axis of said nozzle; a plurality of passageways in saidbase, each passageway communicating at one end with an interior of saidhollow base and communicating at another end externally of said base andsaid pin in the vicinity of a junction between said pin and said base; aflexible seal of resilient material mounted on said base adjacent aforward end thereof and extending outwardly of said base away from saidaxis; said seal having a forwardly facing flat face for engaging andsealing against said wall externally of said hole when said pin isinserted in said hole; and said forwardly facing face having an innerperiphery surrounded by an outer periphery, and said face having atleast one escape groove therein extending away from said axis from saidinner periphery to said outer periphery to permit escape from said holeof any excess material injected into said hole through said passageways.12. The nozzle of claim 11, wherein said seal is slidably mounted onsaid base for movement therealong away from said pin, and furthercomprising resilient means, mounted on said base, for resilientlybiasing said seal in said forward direction.
 13. The nozzle of claim 12,wherein said seal is mounted on a collar surrounding and slidable alongsaid base, said resilient means comprises a spring surrounding said baseand acting between said collar and a flange on said base rearwardly ofsaid collar.
 14. The nozzle of claim 11, wherein each of saidpassageways extends forwardly from said one end to said another end, theanother ends of said passageways being spaced around and adjacent a rootportion of said pin at said junction between said pin and said base. 15.The nozzle of claim 14, wherein:said another ends are located in aforwardly facing surface of said base at a front end of a bore in saidbase, said bore opening rearwardly at a rear end of said base; said sealis slidably mounted on said base; and further comprising: a springacting between said seal and a flange on said base and resilientlyurging said seal forwardly with respect to said base.
 16. A nozzle forforming a plug in a wall, said nozzle comprising:a screw-threaded hollowbase for detachably screwing the nozzle to a hot melt gun; a tapered pinconnected to and extending away from said base in a forward directionalong a central longitudinal axis of said nozzle; a plurality ofpassageways in said base, each passageway communicating at one end withan interior of said hollow base and communicating at another endexternally of said base and said pin in the vicinity of a junctionbetween said pin and said base; a flexible seal mounted on said baseadjacent a forward end thereof and extending outwardly of said base awayfrom said axis; said seal being slidably mounted on said base formovement therealong away from said pin; resilient means, mounted on saidbase, for resiliently biasing said seal in said forward direction; saidseal having a collar; and said passageways extending outwardly away fromsaid axis with said another end of each passageway being closed by saidcollar in a forward position thereof, rearward movement of said collaraway from said pin opening said another end of each passageway.
 17. Thenozzle of claim 16, wherein said nozzle is mounted on said hot melt gun,said screw-threaded base being threadedly engaged in a correspondinglythreaded tip of said hot melt gun.
 18. A nozzle for forming a plug in awall, said nozzle comprising:a base having an externally threaded hollowrear portion and a hollow forward portion; a pin extending forwardlyfrom said forward portion away from said rear portion; a passagewaythrough said pin, said passageway communicating at a rear end with aninterior of said base, and said passageway opening at a forward endthrough a forward tip of said pin; a seal of resilient material mountedon and surrounding said base forward portion, said seal being conicaland tapering inwardly and forwardly towards said pin; and a plurality ofribs extending outwardly from said seal.
 19. The nozzle of claim 18,wherein:said forward portion has a forward conical portion adjacent saidpin, said forward conical portion forming an extension of said conicalseal; said base forward portion is provided with a pressure plateadjacent said threaded rear portion; and further comprising: aspring-loaded ball valve disposed in said base interior and urgedrearwardly against a valve seat formed in said base interior.